IAU Chart
NOIRLab Images
Stars and Sticks| Abbreviation | Hya |
|---|---|
| Meaning | Sea Serpent |
| Pronunciation Guide is based on “Pronouncing Astronomical Names,” published in 1943 by the American Astronomical Society. | HIGH-druh |
| Genitive The genitive is the Latin possessive form used in star names. For example, Alpha Orionis means “the Alpha of Orion.” | HYE-dree |
| Best Month | April |
| Visibility | Global |
| Origin | AncientThese figures are rooted in the classical Greek and Mesopotamian traditions cataloged by Ptolemy in the 2nd century AD. |
| Author | PtolemyPtolemy, a 2nd-century Greco-Egyptian astronomer, cataloged the 48 classical constellations in his landmark work, the Almagest. These form the core of the 88 modern constellations recognized today. |
| Type | constellation |
| Difficulty | Challenging |
| Description | The Water Snake is the largest of all 88 constellations by area, stretching an enormous 100 degrees across the sky — over a quarter of the full celestial equator. In myth it was the monstrous swamp serpent of Lerna with so many heads that for every one Hercules cut off, two grew back; he only defeated it by cauterizing each stump with fire. The constellation extends so far that it takes over six hours to completely rise above the horizon. Despite its vast size it is surprisingly faint; its brightest star, Alphard ('the solitary one' in Arabic), is an orange giant about 177 light-years away that shines alone in an otherwise empty region of sky. |
Click a thumbnail to view full-size. Plain and Annotated versions available on the image page.
Monthly sky charts courtesy of What's Out Tonight? — Copyright ©2026 Ken Graun. Star charts are optimized for mid-latitudes of the Northern Hemisphere. Click a chart to view or download the PDF. For guidance on using the chart, or to purchase a planisphere and astronomy books, visit kenpress.com.
Images: NOIRLab/NSF/AURA/E. Slawik · IAU and Sky & Telescope · Stellarium — Full credits →
